My employer blackmailing me for non issurance of relieving and experience letter.

I am working in a proprietor firm for last 2.8 years and I am in a bond. Bond states that I need to serve 60 days notice period and pay a certain amount of penalty amount. I am ready to pay the penalty amount and serve the notice period. I have resigned from the organisation and send a copy of resignation letter to HR, as well as CEO via email and registered post. I haven't received any response and further mailed them about the last working day confirmation. They are saying i need to please certain people regarding the project. When I am asking for the last working day confirmation i got a response from the CEO stating a blackmail. My resignation email. First email: Hi Navin, Please accept this letter as a formal notice of resignation from the company (OPTIONMATRIX INFOTECH) as a software engineer on 29th of December 2020. As discussed please consider my leave balance into my notice period. Requesting you to provide me the last working day. Second email: Hi, As you are aware that I have submitted the resignation on 29th of December 2020 and the communication is sent to you by email but there was no response / reply from your end confirming my last working day which Ideally falls on 26th feb 2021. As Discussed I am ready to pay the penalty amount for the breach of contract, and serve the required notice period as per the agreement and the same is mentioned above. Also please confirm the date for full and final settlement of arrears due to me by the company (OPTION MATRIX INFOTECH) which includes salary for DEC'2020, Salary for the Notice Period served, Leave encashment and the Provident Fund. ________________ I haven't got any response to the mail. When I asked this over skype for the last confirmation, i received the below message. Respond from CEO: Please note that I am not under any legal obligation to give you a relieving letter or experience letter now or in future.It is in your interest to ensure win win and maintain a good relationship with the company. Else you can consider removing the Option Matrix experience from your resume because I will not give a positive reference in return for this kind of constant nuisance and argument you are creating in the company every day. With out the last working day confirmation I may loose the oppurtunity with my new employer.